A human rights lawyer has been detained for six months after defending Chinese churches in their fight against demolition and cross removal.

Zhang Kai was taken by police from a Christian church in Wenzhou, in the province of Zhejiang. Chinese attorneys have confirmed Zhang has been confined to six months of residential surveillance on suspicion of "endangering state security" and "disturbing the public order."

These are two charges frequently brought against dissidents in China and are used to prevent lawyers meeting with their clients.

Residential surveillance usually means "hotels, so the investigators can contact the parties directly," said another rights protection lawyer, Liu Xiaoyuan.

"The party is left alone in the room, and the investigator keeps watch on him every day. This causes more psychological stress."

Zhang had been representing churches which have been battling official attempts to tear down crucifixes and houses of worship in Wenzhou.

After taking away Zhang and two assistants, Wenzhou police also detained more than 10 Christians, including pastors, human rights activists told Voice of America. Some have since been released, but most are still in custody.

Bob Fu, the founder and president of China Aid, a Christian human rights organisation, told Christian Today of his outrage at the sentence.

"This represents a new low on the rule of law in China," Fu said. "They did nothing but legally defend hundreds of church's crosses from being barbarically demolished.

"The international community, especially President Obama, should make it clear to President Xi Jinping [that] these acts of total disregard to basic human rights and religious freedom should and will be condemned by all during Xi's planned visit to the United Nations and U.S. next month."

According to religious rights groups, about 1,500 crucifixes have been torn down in Zhejiang province, which includes Wenzhou. Several churches have been demolished.